US&S searchlight signals can be either pole or ground mounted. The pole and ground mounting hardware is interchangeable between the different searchlight signal styles.  All that is required to replace the mounting hardware is the removal of a pin on each side of the signal case and the bottom nut on the adjustment bolt.

There are two kinds of mast mounts.  The first is used for top of mast mounting.  With this mount, the signal is placed in front of and at the very top of the mast such that the top of the mast supports the signal door when the door is opened.  The second mast mount is used for side of mast mounting.  It is similar to the top of the mast mount with the exception that it is a bit shorter in length.  This allows the signal to be mounted closer to the side of the mast.  To date, I have only seen top of mast mounts and have to believe that these were used widely for side of mast signal mounting as well.

US&S searchlight signals come with two styles of visors or “hoods”. One is shorter and used mainly, but not exclusively, with ground mounted or “dwarf" signals  The other is longer and used with mast mounted or "high" signals.

The background on US&S mast mounted signals is approximately 35 inches in diameter. It has a characteristic rib on the outer perimeter for added strength.  A smaller 18 inch background is also made, but I believe its use was extremely rare.  It also has the characteristic rib.

Almost all of the US&S searchlight signal housings put into service were made from cast iron.  Newer installations have cast aluminum housings.  The visors and backgrounds are steel.

The early searchlight signals had a gasket on the back door made of a rope-like material impregnated with a heavy wax.  Later signals replaced this rope seal with neoprene, a rubber like material similar to the gaskets used on car doors..

Above.  Ground mounted signal with short visor, phakill unit and inclined prism-less cover glass.  The standard ground mount installation would have a cover glass with linear deflecting prisms located on the outside face of the glass to deflect the light upward by 10 degrees.

Above.  Background or target showing characteristic stiffening rib on the perimeter.

Below.  Rare double stack ground mounted unit.  Note the “ears” cast into the lower H-2 case.  The upper unit also has a unique base mount to fit on top of the ears on the lower case.

Above.  Ground or dwarf base.  This typically bolts onto a concrete foundation.  The slotted bolt holes are needed to fine tune the direction of the signal.  The signal elevation is adjusted with the front bolt and nuts.  Note the characteristic D shaped washer found on all US&S searchlight signals.

Above and below.  Two views of mast mounting hardware.  These signals are usually mounted on five or six inch diameter poles.  The poles pictured are only four inches.  The signal on bottom needs some paint.

Above.  Sighting device used to finely position mast mounted searchlight signals.  The front hole contains a metal cross.  The back hold contains a metal plate with a pin hole.  The placement of the pin hole is critical to the accuracy of the sighting device and probably would have been made or “calibrated” at the factory as part of the manufacturing process.  A hole in the target accommodates viewing.  Note the rope gasket on the back door.

Above.  Close-up view of the interconnection between the signal units.  Note the large conduit connecting the bottom of the upper signal case to the side of the  lower signal case.  The ground mount also differs in that it accommodates the adjustment mechanism used in the typical mast mounted signal.  This is likely a more modern ground mount design.  As the photos indicate, some prefer silver colored signals.